DE102006054587A1 - Procedure for bringing locally defined weakened section in spacer fabric by laser beams of carbon dioxide-laser useful in motor vehicle, by pre-treating the area surrounding the weakened section, and dyeing- and metallizing the section - Google Patents

Abstract

The procedure for bringing a locally defined weakened section in a spacer fabric (1) by laser beams (4) of a carbon dioxide-laser with a capacity of = 2000 Watts useful in a motor vehicle, comprises pre-treating the areas (5a, 5b) surrounding the weakened section for increasing the resistance according to the irradiation by the laser beam at 80-120[deg] C, dyeing and metallizing the weakened section, spraying the weakened section with a flame retardant, bringing a metal or metalized thread (6a, 6b) into the weakened areas and flushing the weakened section with carbon dioxide or nitrogen. The procedure for bringing a locally defined weakened section in a spacer fabric (1) by laser beams (4) of a carbon dioxide-laser with a capacity of = 2000 Watts useful in a motor vehicle, comprises pre-treating the areas (5a, 5b) surrounding the weakened section for increasing the resistance according to the irradiation by the laser beam at 80-120[deg] C, dyeing and metallizing the weakened section, spraying the weakened section with a flame retardant, bringing a metal or metalized thread (6a, 6b) into the weakened areas and flushing the weakened section with carbon dioxide or nitrogen. The spacer fabric consists of spacer fibers (8) arranged between two cover layers (7a, 7b). The thread differentiates the spacer fibers and/or the cover layers with respect to color and/or structure. The thread contains a fire-proofed coating and is manufactured under addition of a flame protection agent. The thread consists of highly reinforced polymers. The weakened section is treated with an energy-rich radiation for secondary cross-linking of the plastics of the spacer fabric. The temperature of the areas of the weakened section is lowered to -40 to -30[deg] C. The spacer fabric is part of a multilevel decoration compound. The weakened section forms an airbag tear seam. An independent claim is included for an interior equipment part for a motor vehicle with a decoration compound.

Description

Field of the invention

The The present invention relates to a method for introducing at least one locally limited weakening in a spacer knitted fabric, in particular for use in a motor vehicle, by means of one or more laser beams, wherein the spacer knitted fabric consists of spaced between two cover layers spacing fibers.

State of the art

The Introducing partial weakenings in areal Materials, especially for Composite materials, as in the decorative area, preferably in motor vehicles Use is sufficient known. Such weakenings are mainly introduced there in decorative composites, where, for example in the case of triggering an airbag or in a crash of a motor vehicle, the decor to tear along pre-defined lines, so injury of the motor vehicle occupant to avoid or the free and unhindered deployment of the airbag to ensure.

When Decor materials are currently in motor vehicles and here, for example in the area of the instrument panel of door linings, center consoles or similar material composites of a substantially dimensionally stable Decor carrier and one about it arranged decorative material used. This customary decorative materials are For example, any kind of plastic, especially in foil form and strength, Leather or leather-like Materials, wood veneers or the like.

Between the decor carrier and the decor material are also for setting a particularly advantageous feel of the decor one or more layers arranged with a greater softness. In this case, in particular spacer knitted fabrics, which consist of two of a layer of spaced apart fibers interconnected Cover layers exist, proved to be particularly advantageous.

The structure and the materials of such spacer fabrics are well known to the skilled person and, for example, in the EP 0617152 B1 described. This document also mentions manufacturing processes and uses for spacer fabrics.

The Introduction of material weakenings in the flat used as decor Materials were initially using a milling tool, a knife or like. About that there were already approaches the weakenings by means of one or more laser beams in the composite material or to introduce individual layers thereof, which in particular the accuracy in litigation and the possibilities in the design of the weakening geometries increased.

Just the targeted laser weakening However, spacer fabrics are extremely difficult. This is due to that despite the aligned arrangement of the spacer fibers between the cover layers of the spacer knitted fabric their position and orientation not exactly defined. this leads to to that, despite a fixed laser path, the wales in be weakened differently and also a different one and possibly undefined material erosion is effected. This leads again to different mechanical properties, for example Tensile or elongation values in the spacer knitted fabric and finally in the entire decor composite.

This is particularly harmful because the spacer fabric usually the biggest tear resistance within a decorative material and so different Property values have a particularly large influence on the properties of the entire decor composite have. Such values usually become as part of functional tests, such as airbag function tests determined and should be subject to a very small tolerance fluctuation.

One Another disadvantage of a different Materialabbrands on the Length and / or Width of a weakened area can be seen in the fact that such differences, if necessary, to a partially enlarged gap opening in Decorating lead what in the worst case Fall on the laminated parts signs and thus the appearance a decorative composite worsened lasting.

In In practice, so far a spacer knitted fabric by means of one or more Laser beams weakened, wherein between lasered perforation holes a support material in the form of supporting bars remains. These support bars However, when airbag shot show a very high elongation behavior, which in turn causes the bulge the decorative material or an unclean, for example, wave-shaped cracking behavior leads in the decorative composite. But this is especially true in areas that are particularly sensitive to security, for example, in decorative composites that are above airbag flaps are arranged, particularly disadvantageous, because thereby the unfolding behavior of Airbags can be obstructed.

Object of the invention

It was therefore an object of the invention to provide a method by means of which a spacer knitted fabric can be weakened by using one or more laser beams, without an uncontrolled material erosion beyond the desired weakened areas and also by the appearance of a decorative composite can be ensured at a high level.

These Task is in accordance with the invention solved by a method having the features of claim 1. advantageous Embodiments of the method according to the invention can be found in the dependent Claims.

The Method according to the invention is at the introduction of at least a localized weakening in a flat Spacer knit, as in the aforementioned prior art is described, applied. Bring one or more laser beams successively or simultaneously weakening areas in the spacer knitted fabric one that has been pretreated in advance so that at least those Areas directly adjacent to the weakenings to be introduced are arranged, a higher Resistance to have the laser beams. Thus it is guaranteed that the weakening within the previously defined geometries is introduced and also is limited to the predefined locations.

The Invention thus offers a particularly simple way compared to the Prior art improved functional property of the spacer fabric and allows a purposeful weakening of the Spacer knitted fabrics only in the pre-defined areas. By the targeted pretreatment of the spacer knit can also be a clean Crack behavior and especially a sudden tear along predefined weakening lines and without any bulging be achieved by parts of the decor composite.

The Invention thus provides a very simple means Improvement over the prior art. Moreover can pretreatment over a variety of different process steps take place, wherein however, of course the appropriate combination of several of the below Method particularly advantageous results can be achieved.

The Invention is used particularly advantageously in spacer fabrics can be which form part of a multilayer decorative composite. such multilayer decorative composites are used in particular in motor vehicle construction to cover flat Interior trim or the like used. Preferred installation locations are for this especially the instrument panel, the center console or door interior trim in the motor vehicle.

The used materials and composite materials are well known to those skilled in the art. When Decorative materials that usually have such a decorative composite close to the visible side are Plastic or decorative leather or leather-like decorations Material widely used. As plastic decorations here are particularly planed, Materials of PVC, PU, TPO or TPO foam preferred.

The usual used decor carrier materials are ABS or ABS blends, PP GF or LFI carrier, which are optionally additionally fiber-reinforced.

Between decorative support and decorative material are one or more layers of upholstery arranged, wherein the invention specifically to such decorative composites is directed, in which the padding at least at least one Layer of spacer knitted fabric comprises.

Additional wise Such decorative composites between the individual layers of decor carrier, decor and cushion layer each have a layer of adhesive and / or a bonding agent on to a durable, dimensionally stable and also resistant to shearing forces To create a decorative composite.

The in the spacer knit and thus possibly at least parts the decorative composite introduced weakenings form preferably an airbag tear seam out.

Preferably, the weakenings are introduced by means of one or more CO ₂ lasers, which preferably have a power of ≦ 2000 watts. In this case, a method is provided with conventional and available on the market, in which the performance of the laser is particularly well adapted to the materials and material thicknesses usually available in spacer fabrics. In particular, when using such a laser also avoided that metal stencils, which are used for example for clamping or holding down the spacer fabric or for guiding the laser can be damaged by the laser beam or even penetrated.

As already mentioned at the beginning, allows the invention involves the use of a variety of suitable pretreatments to increase the resistance of the weakening surrounding areas opposite the radiation introduced into the material by means of the laser beams.

In a first preferred embodiment In the form of the method according to the invention, at least one additional thread is introduced into the regions in the vicinity of the weakenings: this can be done both in the region between the cover layers of the spacer fabric, thus in the sub-layer of the spacer fabric formed by the spacer fibers, and in that an additional thread arranged, for example, parallel to an elongated weakening rests on at least one cover layer or is woven into this.

The Incorporation of a thread with one opposite the usually transparent one Fibers of the spacer fabric of different absorbency, such as z. B. by a different color, thus allowing the setting of a different transmission behavior for the laser compared to transparent base material.

Of the Thread can also along a series of punctiform weakenings in the spacer fabric parallel to the aligned series of weakenings be arranged. In this case, the additional thread as a support thread between the lasered weakenings preserved and thus a visible sign of the weakening prevent in the decorative material. This will be particularly advantageous supports, if the spacer thread is modified in such a way that it across from an elevated one Temperature resistant becomes.

In a further particularly preferred embodiment of the method according to the invention the thread is a metal thread or a metallized thread that is called a metallic coated thread. This will not just one significant increase in strength those areas surrounding the weakenings in the spacer knit achieved, but also a particularly heat-resistant structure to disposal placed, due to the metallic luster a not insignificant Part of incident laser light reflects and so a complete absorption prevents the introduced laser energy just in the area, in which the thread is arranged.

In a further particularly preferred embodiment of the method according to the invention the thread has a flame retardant coating and is in full particularly preferably with the addition of a flame retardant been prepared. This is achieved by simple means that possibly at the introduction of the weakenings Laser flames do not damage the thread so much that he loses his functions.

In an alternative embodiment of the invention, the thread also made of high temperature resistant Materials, preferably high performance polymers exist. hereby is a thread available put, the most cost-effective manufacture, the manufacturer particularly many freedoms in relation on the shaping leaves and moreover all can fully meet the requirements imposed on the thread.

As already mentioned at the beginning, may be providing a thread with more than one of the above individually listed Features for the particular application be particularly advantageous. The invention is therefore not alone on alternative embodiments of the above specified characteristics of an additional limited in the spacer fabric introduced thread.

In a further preferred embodiment of the method according to the invention Be the areas that are at least in close proximity to the weakening or the weakenings lie which are to be introduced into the spacer knit, before the laser in suitable Way dyed and / or metallized. This also achieves that the transmission behavior and the absorbency the weakening surrounding areas opposite the material that burned when exposed to the laser beam or is evaporated, be changed particularly advantageous.

These Areas can also and optionally in addition for coloring and / or metallization with a flame retardant sprayed. As a result, the formation or propagation of flames within the distance knitted fabric with particularly simple means or inhibited even prevented. In addition, in such a spray order preferably no particularly high demands on the application amount and the place of application of the flame retardant agent.

According to one also have preferred embodiment of the method according to the invention the spacer fibers and / or at least one of the cover layers of the spacer knitted fabric in the weakenings surrounding areas an increased Thickness up. This will optionally without the need a post-processing and / or addition of additional funds a spacer knitted fabric in which the weakenings are also created limit to the predefined locations. In the episode lies a spacer fabric before, after joining a decorative composite a uniform and shapely weakening that has the quality does not diminish the appearance of the decorative composite.

According to a further approach to the achievement of the above-mentioned goal takes place at at least in subregions of the spacer fabric, thus in the spacer fibers and / or at least one of the cover layers of the spacer fabric and at least in the areas surrounding the weakening prior to introduction of the weakenings by means of one or more laser beams treatment with high-energy radiation, the post-crosslinking of the plastics of the spacer fabric should cause. A person skilled in the art will be aware of the temperatures and holding times required for achieving the purpose for the respective customary plastics. In this way, the mechanical properties of the spacer knitted fabric in localized limited sections can be adjusted selectively and without the addition of additives and without any change in shape of at least parts of the spacer knitted fabric in such a way that there is a knitted spacer fabric which is dimensionally stable in terms of expansion and geometry.

In a further advantageous embodiment of the method according to the invention the temperature of the knitted fabric before the introduction of the weakening increased by laser or lowered, so as to change the material properties targeted. The change the temperature of the flat Material opposite The ambient temperature, whether by heating or cooling, can rise to any one skilled in the art Art done. For example, the application of a heat or cold current on the spacer knitted fabric, the irradiation of the spacer knitted fabric by means of Called infrared lamps or the like. Particularly preferred but a method in which the pre-tempering by cooling or Heat in a device defining a receiving cavity, at least supports becomes.

Preferably For example, the spacer fabric is cooled to a temperature in the range of -40 ° C to 0 ° C, preferably -40 ° C to -30 ° C. in this connection is exploited that on decor composites for use in motor vehicles, their at least essential part of the invention treated Can be made of spacer fabric, requirements in terms of the durability in case of thermal cycling regularly require temperatures of up to -40 ° C. For example, an airbag shot must be in a temperature window safe from -40 ° C to + 85 ° C and almost independent guaranteed by the temperature be.

at the preferred temperature of -40 ° C to 0 ° C and especially preferably from -40 ° C to -30 ° C is beyond guaranteed in each case that the heat generated during the laser process improves with respect to spacer fabrics at room temperature dissipated can be. About that In addition, it comes in the advantageous temperature range to a less material erosion and thus less signage the weakening on the decor side.

In an alternative and equally preferred embodiment of the inventive method However, the spacer knit is at a temperature in the range of + 50 ° C to + 120 ° C, especially preferably from + 80 ° C up to + 120 ° C heated. Again, it is advantageous that in motor vehicles as Decor materials used composites regularly temperatures from up to + 120 ° C have to resist being an invisible in climate change tests of automobile companies damage of the decoration in the temperature range of -35 ° C to + 120 ° C is expected.

In However, the most preferred range of + 50 ° C to + 120 ° C and in particular from + 80 ° C to + 120 ° C is In any case, it ensures that the component has its material properties such changes that it is sufficiently "soft" for laser processing is, so the weakening at significantly reduced laser power and thus also reduced energy input can be realized. This will also be a significantly reduced local material burn in the immediate vicinity of the weakened area causes what finally to a less visible sign of the weakening the decorative side leads.

The Advantages of heating one over the room temperature significantly heated Dekorverbunds are based on the knowledge that when the decor composite is "softened" as it were by the increase in temperature, for the introduction of the weakening or weakenings Laser required energy can be significantly reduced. This finally leads to a significantly reduced burn off of which the weakening areas surrounded materials.

A Lowering the temperature of the decorative composite before introducing the Weakenings by means of Laser in turn causes a "freezing" of those areas the decorative composite, then into the means of or the laser the energy is introduced. This causes a significantly higher energy input in which the weakenings surrounding areas would be required to ignite them. moreover The ambient areas with lowered temperature cause freezing of the weakening area and, where appropriate, melting in the peripheral areas of the Weaknesses.

The method according to the invention is particularly advantageous when the discharge of the exhaust gases is assisted by the fact that a gas flow from the outside at least through the weakened area and surrounding areas is initiated. This can be done, for example, by causing a gas flow by applying a negative pressure or overpressure on one side of the spacer fabric between the cover layers.

hereby Not just those burning or evaporating materials when introducing the weakenings by means Laser generated exhaust gases safely and effectively from the spacer fabric led out; with suitable adjustment of the flow rate within the relevant Parts of the decor composite can also all ciders in the form of soot particles or the like, also completely removed from the spacer fabric become.

In most particularly preferred are those by the Abstandsgwirke passed through gases that combustion within the At least suppress or completely prevent spacer fabrics. this will in a familiar to the expert Achieved by the fact that the oxygen partial pressure in the relevant Areas as far as possible is lowered.

Most preferred, however, is a process wherein inert gases are passed through the spacer fabric, thus those gases which do not interact with any of the materials with which they come into contact. Particularly preferred examples of such gases are CO ₂ , nitrogen, helium, argon or the like and any mixture thereof.

In summary allows the invention by an optionally invisible setting of Material properties in the weakening areas surrounding material areas and along a line or a plurality of juxtaposed ones Lines to narrow the laser track by the given means and the weakening hereby to optimize.

Brief description of the drawings

The The invention will be explained in more detail below with reference to two figures, in FIG those preferred embodiment of according to the inventive method produced spacer knitted fabrics are shown. These embodiments are but by no means suitable to the scope of the invention, as he is in the attached claims is defined in any way restrict.

In the figures shows:

1 a schematic plan view of a spacer knitted fabric according to an embodiment of the invention, and

2 a schematic cross-sectional view of a weakened using a method according to the invention distance knitted fabric.

Ways to execute the invention

In 1 is the top view of the top layer 7a a spacer knit 1 represented, wherein in this embodiment two metal threads 6a . 6b through the top layer 7a were pulled through. Between the threads arranged substantially parallel to one another 6a . 6b Then, by means of a laser (not shown) a weakening in the spacer knitted fabric 1 introduced so that the threads 6a . 6b as a limit to the above the thread 6a and below the thread 6b arranged environments of the weakening area 2 act. In the figure, moreover, two areas 5a . 5b shown in which both the spacer fibers 8th (of which only one is shown here by way of example in cross-section) and the fibers of the cover layer 7a were sprayed with a flame-retardant liquid material before the attenuation is introduced by means of lasers.

In 2 is a schematic cross-sectional view of a spacer knitted fabric 1 shown that from an upper cover layer 7a , a lower cover layer 7b and arranged therebetween and substantially perpendicular to the cover layers 7a . 7b standing spacer fibers 8th consists. It should be noted in particular that the representation of the spacer fibers with a series of large "X's" no reference to the number or arrangement of the spacer fiber 8th but merely to illustrate the distance knit fabric according to the invention 1 should serve. Through the spacer fabric 1 There is a multitude of weakenings 2 introduced by means of (not shown) laser, these weakenings 2 dot-shaped and aligned with each other to follow a predetermined line. The weakenings 2 run through the entire spacer knitted fabric 1 through, wherein in the sub-layer of spacer fiber 8th a bulge of weakening 2 is to be recorded, which when using the method according to the invention negligible influence on the shape retention and the appearance of a decorative composite, the illustrated spacer knitted fabric 1 comprises.

Claims (18)

Method for introducing at least one localized weakening ( 2 ) in a spacer knitted fabric ( 1 ), in particular for use in a motor vehicle, by means of one or more laser beams (s) ( 4 ), wherein the spacer knitted fabric ( 1 ) from between two cover layers ( 7a . 7b ) arranged spacer fibers ( 8th ) and before the introduction of the Weakening (s) ( 2 ) the areas surrounding the weakening (s) ( 5 ) a pre-treatment to increase the resistance of these areas ( 5 ) with respect to the irradiation by means of the laser beam (s) ( 4 ) exhibit. Method according to claim 1, characterized in that before the introduction of the weakening (s) ( 2 ) at least one additional thread ( 6 ) into the areas ( 5 ) is introduced. Method according to claim 2, characterized in that the thread ( 6 ) from the spacer fibers ( 8th ) and / or cover layers ( 7a . 7b ) of the spacer knitted fabric ( 1 ) differs in color and / or structure. Method according to one of claims 2 or 3, characterized in that the thread ( 6 ) is a metal thread or a metallized thread. Method according to one of claims 2 to 4, characterized in that the thread ( 6 ) receives a flame retardant coating. Method according to one of claims 2 to 5, characterized in that the thread ( 6 ) is prepared with the addition of a flame retardant. Method according to one of claims 2 to 6, characterized in that the thread ( 6 ) consists of high temperature resistant materials, preferably high performance polymers. Method according to one of the preceding claims, characterized in that the areas ( 5 ) before introducing the weakening (s) ( 2 ) and / or metallized. Method according to one of the preceding claims, characterized in that the areas ( 5 ) before introducing the weakening (s) ( 2 ) are sprayed with a flame retardant. Method according to one of the preceding claims, characterized in that the spacer fibers ( 8th ) and / or at least one of the cover layers ( 7a . 7b ) of the spacer knitted fabric ( 1 ) at least in the weakening (s) ( 2 ) surrounding areas ( 5 ) have an increased thickness. Method according to one of the preceding claims, characterized in that the spacer fibers ( 8th ) and / or at least one of the cover layers ( 7a . 7b ) of the spacer knitted fabric ( 1 ) at least in the weakening (s) ( 2 ) surrounding areas ( 5 ) before introducing the weakening (s) ( 2 ) a treatment with high-energy radiation for the post-crosslinking of the plastics of the spacer knitted fabric ( 1 ) Experienced. Method according to one of the preceding claims, characterized in that the temperature of the regions ( 5 ) before introducing the weakening (s) ( 2 ) relative to the ambient temperature, preferably to a temperature in the range of + 50 ° C to + 120 ° C, more preferably from + 80 ° C to + 120 ° C, is increased. Method according to one of claims 1 to 11, characterized in that the temperature of the regions ( 5 ) before introducing the weakening (s) ( 2 ) relative to the ambient temperature, preferably to a temperature in the range of -40 ° C to 0 ° C, more preferably from -40C to -30 ° C, is lowered. Method according to one of the preceding claims, characterized in that the spacer knitted fabric ( 1 ) Part of a multilayer decorative composite ( 3 ). Method according to one of the preceding claims, characterized in that the weakening (s) ( 2 ) form an airbag tear seam. Method according to one of the preceding claims, characterized in that the weakening (s) ( 2 ) by means of one or more CO ₂ laser, preferably with a power of ≤ 2000 watts, are introduced. Method according to one of the preceding claims, characterized in that during the introduction of the weakening (s) ( 2 ) at least the areas ( 5 ) with a gas, preferably a flame-retardant gas, particularly preferably an inert gas such as CO ₂ or N ₂ , are flushed through. Interior fitting for a motor vehicle having a decorative composite comprising a spacer knitted fabric ( 1 ), prepared by a process according to any one of claims 1 to 17.